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1.
Changes in udder health and antibiotic resistance of mastitis pathogens isolated from dairies upon conversion from conventional to organic management over a 3-year period was studied. Coagulase-negative staphylococci (CNS) were the most prevalent mastitis pathogens isolated. CNS were significantly less resistant to β-lactam antibiotics when isolated from milk after the herd transitioned to organic management. Cessation of the use of antimicrobial therapies in dairies in combination with organic management could lead to a reduction in the antimicrobial resistance of mastitis pathogens.  相似文献   

2.
Treatment of mastitis should be based on bacteriological diagnosis and take national and international guidelines on prudent use of antimicrobials into account. In acute mastitis, where bacteriological diagnosis is not available, treatment should be initiated based on herd data and personal experience. Rapid bacteriological diagnosis would facilitate the proper selection of the antimicrobial. Treating subclinical mastitis with antimicrobials during lactation is seldom economical, because of high treatment costs and generally poor efficacy. All mastitis treatment should be evidence-based, i.e., the efficacy of each product and treatment length should be demonstrated by scientific studies. Use of on-farm written protocols for mastitis treatment promotes a judicious use of antimicrobials and reduces the use of antimicrobials.  相似文献   

3.
Dairy operations in states representing 86% of the United States’ national dairy herd were surveyed regarding the occurrence of common dairy diseases or disorders (digestive, respiratory, gastrointestinal, lameness, mastitis, navel infection) in specified production groups (weaned heifers, unweaned heifers, adult cows), and the most common antimicrobial preparation used to treat these conditions. Within disease and production group, disease frequency and characteristics of primary antimicrobial (drug class, availability, spectrum of activity, extra-label usage, withdrawal times) were compared among herd sizes (30–99, 100–499, and ≥500 cows) using chi-square or t-tests that accounted for the sampling design. The most common diseases were mastitis and lameness in cows, and gastrointestinal disease in unweaned calves, affecting 16, 11, and 15% of the target populations, respectively. Herd-level disease prevalence tended to increase as herd size increased, whereas within-herd prevalence tended to decrease as herd size increased. Broad-spectrum antimicrobials were selected as primary treatments by a majority of operations for nearly all diseases surveyed. When treating gastrointestinal disease, navel infection, or reproductive disorders, a majority of operations selected primary treatments not specifically labeled for that condition. Selection of over-the-counter preparations tended to decrease as herd size increased, whereas selection of broad-spectrum preparations tended to increase with herd size.  相似文献   

4.
AIM: To determine the prevalence of clinical mastitis in spring-calving dairy herds in the Waikato Region of New Zealand and to identify factors associated with variation in the prevalence of clinical mastitis between herds. METHOD: A total of 799 quarters from 595 dairy cows from 38 dairy herds were diagnosed by herd owners as having clinical mastitis between 8 July and 21 August 1997. Quarters diagnosed with clinical mastitis were sampled for bacterial culture and somatic cell count, and the presence of clots in the milk and the presence of udder oedema were assessed by a technician or veterinarian. RESULTS: Clinical mastitis was diagnosed in an average (+/-s.e.m.) of 9.9% (+/-0.8%, range 0.9-21.4%) of calved cows within the herds. Bacteria were not cultured from an average of 12.4 % (+/- 2.0%, range 0.0-45.5%) of cows and 22.3% (+/- 2.4%, range 0.0-54.0%) of quarters diagnosed as having clinical mastitis. There were significant differences between herds in the proportion of cows diagnosed with mastitis and in the proportion of clinical mastitis cases from which bacteria were not cultured. A decreased prevalence of clinical mastitis (p<0.001) was associated with an increased percentage of the herd treated with dry cow antibiotics. An increased prevalence of clinical mastitis (p<0.0001) was associated with both an increased percentage of cows treated in the previous season with lactating cow antibiotics and an increased percentage of heifers in the herd. Herds that were fed supplements before or during lactation had a higher prevalence of clinical mastitis than herds that were not fed supplements (p<0.001). An increased proportion of quarters diagnosed with clinical mastitis that did not culture bacteria was associated with an increased prevalence of clinical mastitis (p<0.001). The proportion of quarters that the technician or veterinarian found with evidence of clinical mastitis (i.e. a somatic cell count >500,000 cells/ml and the presence of either clots or udder oedema) within a herd was inversely related to the proportion of quarters within a herd from which no bacteria were isolated. CONCLUSION: There was a large variation in the prevalence of clinical mastitis and in the proportion of clinical quarters from which no bacteria were grown between herds. Management factors such as the use of dry cow therapy, feeding regimes and heifer replacement rates all affected the prevalence of clinical mastitis. Herd owners appear to differ in the sensitivity and specificity of their diagnosis of clinical mastitis, with bacteria not isolated from up to 50% of quarters diagnosed with clinical mastitis in some herds. Improvements in the specificity of herd owner diagnosis of clinical mastitis may reduce the use of antibiotics for mastitis during lactation and hence may reduce the risk of antibiotic contamination of milk supplied for human consumption.  相似文献   

5.
Administration of antimicrobials to livestock increases the risk of antimicrobial resistance (AMR) in commensal bacteria. Antimicrobials in pig production are usually administered per pen via feed which implies treatment of sick alongside with healthy animals. The objective of this systematic literature review was to investigate the effect of orally administered antimicrobials on AMR in Escherichia coli of swine.  相似文献   

6.
Mastitis remains one the most important diseases in dairy cattle despite the progress made in improving general udder health in recent years. Epidemiological studies have revealed that following treatment with antimicrobials, bacteriological cure rates vary between 0% and 80% but with no evidence of a significant loss of activity of the major classes of antibiotics licensed for the treatment of bovine mastitis. Recurrent infections are often attributable to biofilm growth of bacteria and this review provides an overview of those mechanisms related to bacterial biofilm growth in mastitis. Biofilm formation is accompanied by significant genetic and subsequent physiological changes in the microorganisms resulting, inter alia, in a loss of sensitivity to virtually all classes of antibiotics.  相似文献   

7.
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8.
Concerns exist that some uses of antimicrobials in cattle may lead to the emergence, proliferation, dissemination and persistence of resistant pathogenic bacteria in animal agriculture, which in turn can infect humans via the food supply. The degree of perceived risk varies with the clinical indication for which the antimicrobial in question is used. In this study, four uses of antimicrobials are considered, including in acutely sick, chronically sick, at-risk, and high-risk cattle, contrasting the degree of risk among these uses. Using a random sample of 103 feedlot cattle veterinarians and variables drawn from the theory of planned behavior, we predict differences in risk perception by clinical indication with differences in perceived efficacy of antimicrobials, social pressures to use antimicrobials, and moral obligations to use antimicrobials. In most models, veterinarians who perceived that others in the feedlot industry (i.e., other feedlot veterinarians, nutritionists, feedlot clients, and retained owners of cattle) were more likely to expect them to use antimicrobials in one situation versus another, the less likely those veterinarians perceived the risk of antimicrobial risk to be greater in the former versus the latter situation. Only two of these contrasts contained influences outside the immediate feedlot relationships. This exception involves the 'downstream' public: meat packers, retailers, and consumers. Veterinarians who believe that using antimicrobials for acutely sick cattle is more beneficial than using antimicrobials for chronically sick cattle were more likely to believe that antimicrobial resistance was a less probable outcome in acutely sick cattle than in chronically sick cattle.  相似文献   

9.
The vast literature on antimicrobial drug use in animals has expanded considerably recently as the antimicrobial resistance (AMR) crisis in human medicine leads to questions about all usage of antimicrobial drugs, including long-term usage in intensively managed food animals for growth promotion and disease prevention. Attention is also increasingly focusing on antimicrobial use and on bacterial resistance in companion animals, which are in intimate contact with the human population. They may share resistant bacteria with their owners, amplify resistant bacteria acquired from their owners, and act as a reservoir for human infection. Considerable effort is being made to describe the basis of AMR in bacterial pathogens of animals. Documentation of many aspects of use of antimicrobials in animals is, however, generally less developed and only a few countries can describe quantities of drugs used in animals to kg levels annually. In recent years, many national veterinary associations have produced 'prudent use guidelines' to try to improve antimicrobial drug use and decrease resistance, but the impact of guidelines is unknown. Within the evolving global movement for 'antimicrobial stewardship', there is considerable scope to improve many aspects of antimicrobial use in animals, including infection control and reduction of use, with a view to reducing resistance and its spread, and to preserving antimicrobial drugs for the future.  相似文献   

10.
This paper reviews common therapeutic applications of antimicrobials in broiler chicken production in relation to Canadian guidelines, surveillance data, and emerging public health concerns about antimicrobial use (AMU). Escherichia coli, Clostridium perfringens, and Staphylococcus spp., were reviewed because of their animal health and economic significance. Enterococcus cecorum and Salmonella were included because of their importance in antimicrobial resistance (AMR) surveillance. This review identified that i) antimicrobials are available in Canada to treat infections by these agents, but may be through over the counter or extra-label use, ii) prevalence rates for these diseases are unknown, iii) antimicrobial use estimates in broilers are lacking, and iv) AMR has emerged in clinical isolates, though data are very sparse. This review highlights the need for surveillance of AMU and AMR in broiler chickens in Canada.  相似文献   

11.
Sources of Prototheca spp in a dairy herd environment   总被引：1，自引：0，他引：1  
A source of Prototheca spp causing mastitis in a herd of 263 milking cows in North Carolina was investigated. Of 38 samples from the dairy environment, 18 (47%) contained Prototheca spp. Isolation sites included cattle drinking water; a feed trough; mud, dirt, and excreted feces from a dirt lounging area; water, sludge, mud, and vegetation from a creek in the lounging area; and the floor of a freestall barn. Samples were collected from 5 additional dairies, including one dairy with and 4 dairies without a history of protothecal mastitis. Prototheca spp were isolated from 48 (25%) of 190 samples from various sites on all 6 dairies. Isolates were P zopfii (45; 94%) and P wickerhamii (3; 6%). Isolation frequency ranged from 4 to 47% of samples/dairy. There was no apparent difference in the isolation frequency of Prototheca spp from samples from dairies with or without a history of protothecal mastitis. Sites characterized by wetness and the presence of organic matter most commonly yielded Prototheca spp. Because Prototheca spp appear to be common in the dairy environment, factors in addition to presence in the environment may be important in development of protothecal mastitis.  相似文献   

12.
Between December 1985 and March 1987 an enzyme-linked immunosorbent assay (ELISA) was used with 3774 sera to estimate the prevalence of antibodies to Mycoplasma bovis in sera from three age groups of cattle in four dairies in California and to test for possible associations between the presence of M. bovis antibodies and the age or breed of the cattle and the farm. Unadjusted and adjusted associations were evaluated using the -square test for associations and multiple logistic regression analysis, respectively.There was a tendency for the proportion of cattle seropositive for M. bovis to increase steadily and approximately linearly with age (p<0.05). There was also a statistically significant relationship bbetween a M. bovis seropositive test and being from Farm IV (p<0.05). Farm IV was the largest of the four dairies and this association may be due to the effect of herd size.These findings confirm the ubiquitous distribution of antibodies to M. bovis in dairy cattle in California and also support previous reports of herd size as an important factor in mycoplasmal mastitis.  相似文献   

13.
Antimicrobials are essential medicines for the treatment of many microbial infections in humans and animals. Only a small number of antimicrobial agents with new mechanisms of action have been authorized in recent years for use in either humans or animals. Antimicrobial resistance (AMR) arising from the use of antimicrobial agents in veterinary medicine is a concern for public health due to the detection of increasing levels of resistance in foodborne zoonotic bacteria, particularly gram‐negative bacteria, and due to the detection of determinants of resistance such as Extended‐spectrum beta‐lactamases (ESBL) in bacteria from animals and in foodstuffs of animal origin. The importance and the extent of the emergence and spread of AMR from animals to humans has yet to be quantified. Likewise, the relative contribution that the use of antimicrobial agents in animals makes to the overall risk to human from AMR is currently a subject of debate that can only be resolved through further research. Nevertheless, risk managers have agreed that the impact on public health of the use of antimicrobials in animals should be minimized as far as possible and a variety of measures have been introduced by different authorities in the EU to achieve this objective. This article reviews a range of measures that have been implemented within European countries to reduce the occurrence and the risk of transmission of AMR to humans following the use of antimicrobial agents in animals and briefly describes some of the alternatives to the use of antimicrobial agents that are being developed.  相似文献   

14.
Wildlife can contribute to environmental contamination with bacterial pathogens and their transfer to the human food chain. Global usage and frequent misuse of antimicrobials contribute to emergence of new antimicrobial resistant (AMR) strains of foodborne pathogens. We conducted a scoping review of published research to identify and characterize the evidence on wildlife's role in transmission of AMR and/or bacterial pathogens to the food chain. An advisory group (AG) of 13 North American experts from diverse disciplines was surveyed to solicit insight in the review scope, priority topics and research characteristics. A pre‐tested search strategy was implemented in seven bibliographic databases (1990 to January 2013). Citations were relevance screened, and key characteristics on priority topics extracted independently by two reviewers. Analysis identified topic areas with solid evidence and main knowledge gaps. North America reported 30% of 866 relevant articles. The prevalence of five targeted bacterial pathogens and/or AMR in any pathogen in wildlife was reported in 582 articles. Transmission risk factors for selected bacteria or AMR in any bacteria were reported in 300. Interventions to control transmission were discussed in 124 articles and formally evaluated in 50. The majority of primary research investigated birds, cervids, rodents, feral pigs, opossums, E. coli (n = 329), Salmonella (n = 293) and Campylobacter (n = 124). An association between wildlife and transmission of bacterial pathogens and/or AMR to the food chain was supported in 122 studies. The scoping review identified a significant body of research on the role of wild birds in the prevalence and transmission of E. coli, Salmonella and Campylobacter. There was little research employing molecular methods contributing to the evidence concerning the importance and direction of transmission of wildlife/pathogen combinations. Given the advancements of these methods, future research should focus in this area to help prioritize future intervention studies and risk mitigation strategies.  相似文献   

15.
Distillers grains, a coproduct of ethanol production from cereal grains, are composed principally of the bran, protein, and germ fractions and are commonly supplemented in ruminant diets. The objective of this study was to assess the effect of feeding wet distillers grains with solubles (WDGS) and monensin and tylosin on the prevalence and antimicrobial susceptibilities of fecal foodborne and commensal bacteria in feedlot cattle. Cattle were fed 0 or 25% WDGS in steam-flaked corn-based diets with the addition of no antimicrobials, monensin, or monensin and tylosin. Fecal samples were collected from each animal (n = 370) on d 122 and 136 of the 150-d finishing period and cultured for Escherichia coli O157. Fecal samples were also pooled by pen (n = 54) and cultured for E. coli O157, Salmonella, commensal E. coli, and Enterococcus species. Antimicrobial resistance was assessed by determining antimicrobial susceptibilities of pen bacterial isolates and quantifying antimicrobial resistance genes in fecal samples by real-time PCR. Individual animal prevalence of E. coli O157 in feces collected from cattle fed WDGS was greater (P < 0.001) compared with cattle not fed WDGS on d 122 but not on d 136. There were no treatment effects on the prevalence of E. coli O157 or Salmonella spp. in pooled fecal samples. Antimicrobial susceptibility results showed Enterococcus isolates from cattle fed monensin or monensin and tylosin had greater levels of resistance toward macrolides (P = 0.01). There was no effect of diet or antimicrobials on concentrations of 2 antimicrobial resistance genes, ermB or tetM, in fecal samples. Results from this study indicate that WDGS may have an effect on the prevalence of E. coli O157 and the concentration of selected antimicrobial resistance genes, but does not appear to affect antimicrobial susceptibility patterns in Enterococcus and generic E. coli isolates.  相似文献   

16.
This paper identifies common poultry diseases requiring antimicrobial therapy, antimicrobials deemed efficacious to treat these diseases, and antimicrobial resistance (AMR) in these commodity-pathogen combinations, and describes current residue issues and minor use minor species (MUMS) guidelines. Veterinarians with turkey/layer expertise and diagnosticians were surveyed to determine the bacterial and protozoal diseases diagnosed in the last 5 years. Avian pathogenic Escherichia coli, Staphylococcus aureus, and Ornithobacterium rhinotracheale were the 3 most frequently diagnosed pathogens of turkeys. In layers, E. coli-peritonitis, and Clostridium perfringens/Eimeria spp. infections were the most common diagnoses. A literature review identified 32 antimicrobials as efficacious and/or recommended for treating these diseases. Surveillance and monitoring indicate the presence of enteric resistant organisms from some of these avian species (including resistance to antimicrobials of very high importance to human medicine). This paper highlights the need for surveillance of pathogen frequency, antimicrobial use (AMU), and AMR particularly in turkeys.  相似文献   

17.
The use of antimicrobial drugs in livestock is suspected to contribute to bacterial antimicrobial resistance (AR) development. Dairy farms experiencing recent outbreaks of salmonellosis involving multi-resistant (MR) Salmonella strains were compared to control farms with respect to AR among bovine commensal E. coli isolates. For most antimicrobials tested, the percentage of AR E. coli isolated from salmonellosis-affected farms was significantly higher than that from control farms. Calf E. coli from both case and control farms had greater levels of AR than cow isolates. Commensal E. coli isolates from case farms and calves tended to more frequently be MR. These data are consistent with the existence of higher antimicrobial selection pressure on farms with recent salmonellosis outbreaks, however, the directionality of the relationship remains to be elucidated. An improved understanding of the epidemiology of AR bacteria in livestock production, both at the herd and molecular level, is essential to mitigate risk to public health and food safety.  相似文献   

18.
The dairy herd at Washington State University had an outbreak of mastitis caused by a single strain of Staphylococcus aureus. The outbreak strain, termed novel, could not be controlled with routine contagious mastitis pathogen control procedures (incidence, 3.4 infections/100 cow months; peak prevalence > 22%). Our objective was to implement mastitis control measures that would decrease the incidence and prevalence of intramammary infection (IMI) caused by S aureus in the herd. The following intervention strategies were successfully implemented: strict segregation of cattle with IMI caused by S aureus, intensified culling of cattle with multiple-quarter IMI caused by S aureus, and inducing cessation of lactation of infected quarters in single-mammary-quarter infected cattle. One year after implementation of these control measures, incidence of IMI caused by S aureus was 0.35 infections/100 cow months, and prevalence had decreased from 20 to 8%.  相似文献   

19.
奶牛隐性乳房炎的发生规律及致病菌分离鉴定   总被引：3，自引：1，他引：2  
施飞  魏守海  陈玲  吕程 《中国畜牧兽医》2009,36(10):118-121
作者对四川省彭水县3个奶牛场的泌乳奶牛群进行了隐性乳房炎的检测及其致病菌的分离鉴定,共检测泌乳牛305头次、1131个乳区,隐性乳房炎的个体阳性率为64.92%,乳区阳性率为32.80%,并且其发生率与管理、挤奶卫生及程序、泌乳期、年龄、胎次等有关。致病菌的总检出率为93.48%,其主要病原菌为金黄色葡萄球菌、无乳链球菌和大肠杆菌,分别占总检出率的37.21%、23.26%和13.95%。  相似文献   

20.
OBJECTIVE: To determine factors associated with implementation and use of an on-farm system for bacteriologic culture of milk from cows with lowgrade mastitis, including information on how producers used the on-farm bacteriologic culture system to guide antimicrobial selection practices and the resulting impact on patterns of antimicrobial use. DESIGN: Retrospective cohort study. SAMPLE POPULATION: Producers of 81 dairy farms. PROCEDURE: Farms that used an on-farm system for bacteriologic culture of milk from January 2001 to July 2003 were surveyed. RESULTS: Over half of those producers continuing to use the on-farm culture delayed antimicrobial treatment pending results of bacteriologic culture. Most other producers initiated empirical antimicrobial treatment while bacteriologic culture results were pending. Several barriers to the use of an on-farm system were identified. Significant reductions in rates of antimicrobial use were detected when comparing antimicrobial use rates before and during use of the on-farm system. Most producers chose to treat cows with mastitis caused by gram-positive pathogens with antimicrobials, whereas treatment choices for cows with mastitis caused by gram-negative bacteria and in cases in which no growth was detected varied. CONCLUSIONS AND CLINICAL RELEVANCE: Readily available results permit antimicrobial selections to be made on the basis of the causative agent of mastitis. Adoption of an on-farm system for bacteriologic culture of milk may result in significant reductions in the percentage of cows treated with antimicrobials. Decreasing antimicrobial use may have several benefits including preventing unnecessary discarding of milk, decreasing the potential for drug residues in milk, and improving treatment outcomes as a result of targeted treatments.  相似文献   

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